Is this a WebExtension? Basilisk only has very early WebExtension support based on what was present in FF 52 ESR, and it likely won't be developed any further.

Linux Mint 18.3 Cinnamon (64-bit), Windows 7 (64-bit), Windows 10 build 1803 (64-bit)JavaScript is not Java
"As long as there is someone who will appreciate the work involved in the creation, the effort is time well spent." ~ Tetsuzou Kamadani, Cave Story

storage.sync was implemented in Firefox 53, but the add-on claims compatibility with Firefox 50. I guess that the developer of this add-on should fix the minversion or whatever WebExtensions use to determinate the compatible version range.

I'd actually not call the WebExtension support in Basilisk "very early" since it does cater to most cross-browser WebExtension APIs. The only stuff that isn't in there are the Mozilla-specific APIs (what few of them are actually accepted for implementation by Mozilla, that is) that were added past our fork point, to try and get some semblance of having extension capabilities we already have through our other extension technologies in UXP.

Improving Mozilla code: You know you're on the right track with code changes when you spend the majority of your time deleting code.

"If you want to build a better world for yourself, you have to be willing to build one for everybody." -- Coyote Osborne

Moonchild wrote:I'd actually not call the WebExtension support in Basilisk "very early" since it does cater to most cross-browser WebExtension APIs.

I see. Thanks for the clarification.

Linux Mint 18.3 Cinnamon (64-bit), Windows 7 (64-bit), Windows 10 build 1803 (64-bit)JavaScript is not Java
"As long as there is someone who will appreciate the work involved in the creation, the effort is time well spent." ~ Tetsuzou Kamadani, Cave Story